Much debate exists with regard to the physiological aspects of stuttering. Disturbed laryngeal physiology, in particular, has been speculated to be an integral aspect of stuttering. Fortunately, modern instrumentation such as th flexible fiberoptic naso-laryngoscope (fiberscope) now permit direct observation of laryngeal activity during conversational speech with little or no discomfort. It is proposed that intensive study of laryngeal physiology during stuttering, through the use of a fiberscope, will provide an objective data base from which to evaluate current speculation that the larynx "causes" or is the major contributor to instances of stuttering. Support is sought for two years as a first step of a continuing investigation of the physiology of stuttering. The proposed study will refine and establish an objective description of and information regarding the laryngeal aspects of stuttering. Results of the proposed investigation should impact significantly on current knowledge regarding the physiological aspects of stuttering, especially with regard to the description, diagnosis, and management of laryngeal behavior during stuttering.